Just curious????????????

Yea, sure it can be done, especially as you asked the question.

However, if you'd re-phrased your question to read, "is it possible to do a 1911 tannery 80% frame w/o a mill, PROPERLY?"  

I'd venture to say, NOT!

my 2 cents, (YMMV)
Mike

Yes, it is possible. You'll probably need a dremel tool and some small files to cut the rails which is the hardest part of the project.
You'll have to be very careful and deliberate, but it has been done. Check out www.roderuscustom.tzo.com All kinds of information on completing 0%-80% Sigs/AR15/1911s.

He used a mill,
I was just wondering if there was a way to cut those rails without a mill...

I can't think of how you would do it without one......

Keep looking! There was someone who posted a couple of months ago about finishing a 1911 80% using a set of files.

I've seen postings from a few who have used a dremel on a home-made slide, or who used a sliding table with a drill press. Possible? Yes. Difficult to do it accurately? Also yes.

Your biggest challenge will be to actually get an 80% Tannery frame in hand. Mine has been on order for months and months, with the typical answer to my queries being, "They'll be in in a couple of weeks."  Don't hold your breath.

DeFens...your wait may be coming to an end. William has been shipping his backlog of 1911's for the last couple of weeks and a number of people on the www.rogeruscustom.tzo.com forums have started to receive them.

THE FANCY FRAMES HAVE BEEN SHIPPING AND SOME GI FRAMES BUT I HAVE A WAYS TO GO YET TO GET ALL THE "GI TYPE BACK ORDERDS FILLED

BUT THEY ARE SLOWLY COMMING BACK FROM THE MFG AND GOING OUT

WILLIAM

Of course it's possible.  You could use a shaper, for instance.  
Or, if you think outside the box enough, you can use other means.  For example, one gent here did his with some drawer rails, a piece of plywood, a vise, and a dremel.  
People made many things in metal before we had mills, remember?  
Oh yeah order two frames, in case you fark one up.

That's my problem, I don't think very well outta da box.  

I'm curious to see just how and what methods were used back in the day by colt and remmington, etc....

Here's one Drill Press method...from experience.
Tools:
Drill Press - (A bench-size model like the small Delta brand will work (not as sturdy), but I'd rather use a big floor drill press)

Vise - a cross-sliding machinists vise. Adjust the gibs (the friction plates that are tightened by three or so screws on each side of the slides)to take out as much slop as you can - you probably won't get it all.

The cutting tool - a slitting saw with arbor, endmill, etc. (the more teeth/flutes you have the better the cut...IMHO). If you buy low-end, get one for each side.

Figure out some method to support the frame while it is in the vise with the pressure of the cutter against it.
You can lay it flat on it's side, or stand it up depending on the cutting method you use.
I found the table on a small drill press to be weak. The vise is fairly heavy which would make the table deflect downward. You might need to prop it up level.
TAKE SMALL CUTS!!!!!!!
Don't be in a rush to do this job. Cut, stop & measure often. Don't try to cut to finish specs like this. You can finish up with a file.
I bought Brownell's slide-rail file for twenty-something bucks and was glad to have it... until I figured out that I could grind a small bastard file the same way for cheaper.
Make sure your setup is square to all axis.
Your cuts should be the correct depth and distance from top plane, from one end of the frame to the other. It's not hard to be cutting down hill, or shallow at one end and deep the rest of the way.

Before cutting the rails, you need to decide what point on the frame you are going to measure off of. If it's the top plane, level it off carefully first.

Get a copy of Kuhnhausen's books on the 1911. Someone may think they are pricey for just one frame, but you'll need the information to do things right. He has a video on some aspects of working on a 1911 also.

Buy good parts. I wasn't thrilled with the quality of the DPMS parts kit I purchased (it may have been a freak thing?). Check around on some handguns boards for more parts info.

Gotta go, but I think I covered it all.

Thanks guy,

Did you lay it on the side or stand it up??  Or both?

I clamped mine standing up.
Lots of chatter with the cutter I used (slitting saw [28tooth] with arbor from Grizzly)
I built that frame for use with a .22 conversion slide (like the Ceiner unit).
I used a parts kit from DPMS.
Someday I plan on getting better quality parts, putting a finish on the frame, and shooting it a bit more often.

I used a slitting saw and arbor on mine and it turned out decently - A slightly better slide fit and much smoother than my Brazilian Springfield Armory M1911-A1.  Not the fine target pistol I had hoped for, but it's reliable and fine for defense or combat use.  My biggest mistake was using a 3/32" cutter.  I spent a lot of time with needle files getting the slide and frame to fit.

Based on that and some other recent machining adventures, next time I plan to use a 3/32" or 3 mm keyseat cutter, something around 3/4" - 1" in diameter.  They're much better behaved than slitting saws.  You can easily widen the cut at full depth without having the cutter get weird on you.  I think you could do a steel 1911 frame with one on a drill press (though a mill is much better), if you don't mind putting that kind of stress on your spindle bearings.